The role of different crossover methods when solving the open shop scheduling problem via a simple evolutionary approach

The Open Shop Scheduling Problem (OSSP) is one of the most interesting, complexes and not frequently approached scheduling problems. Due to its intractability with other techniques, in this work we present an evolutionary approach to provide approximate solutions. One of the most important points in an Evolutionary Algorithm is to determine how to represent individuals of the evolving population and then to decide suitable genetic operators. In this work, we use permutations as chromosomes. Dealing with permutations requires appropriate crossover operators to ensure feasible offspring. Usual operators are partially-mapped, order, cycle and onecut- point crossover. The goal is to determine which is the most adequate for facing the OSSP with a simple evolutionary algorithm. Several known instances have been considered for testing in order to evaluate the algorithm behavior.Eje: Sistemas inteligentesRed de Universidades con Carreras en Informática (RedUNCI

Improvement of psychometric properties of a scale measuring inpatient satisfaction with care: a better response rate and a reduction of the ceiling effect

<p>Abstract</p> <p>Background</p> <p>The objective was to solve two problems of an already validated scale measuring inpatient opinion on care: 1) a high non-response rate for some items due to the "not applicable" response option and 2) a skewed score distribution with high ceiling effect.</p> <p>Methods</p> <p>The EQS-H scale ("échelle de qualité des soins en hospitalisation") comprised 26 items and 2 sub-scales of 13 items each, 'quality of medical information' (MI) and 'relationships with staff and daily routine' (RS). Three studies were conducted: a first mono-centre study (n = 552, response rate = 83.4%, self-completion of the scale the day before discharge) to construct a shorter version of the scale without the items with high non-response rate and maintaining those useful to ensure good internal validity (construct, convergent and divergent) and reliability; a second mono-centre study (n = 1246, response rate = 77.9%, self-completion of the scale before discharge) to confirm psychometric properties of the new version; a third multi-centre national study (n = 886, response rate 41.7%, self-completion at home 15 days after discharge) to test a new response pattern in order to reduce ceiling effect.</p> <p>Results</p> <p>Six items having a non-response rate >20% were deleted, increasing rates of exhaustive response to all items from 15% to 48%. Factorial analysis supported the evidence for removing 4 more items to ensure good internal validity and reliability of the new version. These good results (initial variance explained: 43%; Cronbach's α: 0.80 (MI) and 0.81 (RS)) were confirmed by the second study. The new response format produced a normalisation of the 2 scores with a large decrease in ceiling effect (25% to 4% for MI subscale and 61% to 8% for RS). Psychometric properties of the final version were excellent: the 2 subscales (8 items each) explained 66% of the variance in principal component analysis, Cronbach's α were respectively 0.92 (MI) and 0.93 (RS).</p> <p>Conclusion</p> <p>The new version of the EQS-H has better psychometric properties than the previous one. Rates of missing values are lower, and score distribution is normalized. An English version of this scale focused on quality of medical information delivered and on relationship with staff already exists, and this could be useful to conduct cross-cultural studies of health care service quality.</p

Genesis of a Fungal Non-Self Recognition Repertoire

Conspecific allorecognition, the ability for an organism to discriminate its own cells from those of another individual of the same species, has been developed by many organisms. Allorecognition specificities are determined by highly polymorphic genes. The processes by which this extreme polymorphism is generated remain largely unknown. Fungi are able to form heterokaryons by fusion of somatic cells, and somatic non self-recognition is controlled by heterokaryon incompatibility loci (het loci). Herein, we have analyzed the evolutionary features of the het-d and het-e fungal allorecognition genes. In these het genes, allorecognition specificity is determined by a polymorphic WD-repeat domain. We found that het-d and het-e belong to a large gene family with 10 members that all share the WD-repeat domain and show that repeats of all members of the family undergo concerted evolution. It follows that repeat units are constantly exchanged both within and between members of the gene family. As a consequence, high mutation supply in the repeat domain is ensured due to the high total copy number of repeats. We then show that in each repeat four residues located at the protein/protein interaction surface of the WD-repeat domain are under positive diversifying selection. Diversification of het-d and het-e is thus ensured by high mutation supply, followed by reshuffling of the repeats and positive selection for favourable variants. We also propose that RIP, a fungal specific hypermutation process acting specifically on repeated sequences might further enhance mutation supply. The combination of these evolutionary mechanisms constitutes an original process for generating extensive polymorphism at loci that require rapid diversification

[Performance of the Breastfeeding Assessment Score for the prediction of early weaning in France]

National audienceBACKGROUND: The Breastfeeding Assessment Score (BAS) was derived to help identify mothers at increased risk of early weaning in United States. Data are currently lacking on the accuracy of the BAS for French mother-infant pairs. OBJECTIVE: To assess the accuracy of the BAS in a French validation cohort. METHODS: We used the original data from a prospective cohort study of 488 mothers who were breastfeeding at discharge in 9 maternity wards in 2005. The outcome measures were assessed using structured follow-up telephone interviews at 4 and 26 weeks. RESULTS: The weaning rate was 3% at 14 days of infant age. The corresponding area under ROC curve was 0.73 [0.60-0.85] and was comparable to that observed in the derivation cohort (0.75). For a cut point of 8 recommended by the authors of the BAS, 43% of mother-infant pairs were categorized at high risk and the weaning rate in this subgroup was 5%. The mother-infant pairs with a score lower than 8 had a shorter median breastfeeding duration (18 versus 20 weeks, P=0.02), were more likely to report breastfeeding difficulties after discharge (63% versus 53%, P=0.03), and were less likely to be "very satisfied" with breastfeeding experience (66% versus 77%, P=0.007). CONCLUSION: The intrinsic properties of the BAS are robust. However, its use would be of limited interest in France because of the relatively low rate of early weaning. Randomized trials are needed before recommending routine use of BAS-based breastfeeding support intervention